DETERMINATION OF AMINOPYRINE, DIPYRONE AND ITS METABOLITES IN URINE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A readily applicable and accurate isocratic high-performance liquid ch romatography method for the detection of aminopyrine, dipyrone and its metabolites in urine is described. Parent drugs and four metabolites were chloroform-extracted from 1 ml of urine after addition of the int ernal standard isopropylaminoantipyrine and alkalinization. The organi c phase was evaporated to dryness, and the residue was reconstituted i n the mobile phase, which was injected onto a Spherisorb ODS 5 mum par ticle-size column (250 x 4.6 mm) using as mobile phase water, methanol , triethylamine, and acetic acid. The column eluent was monitored by u ltraviolet absorption at 254 nm. Excellent linearity (r > 0.99) was ob tained in the range 1-150 mug/ml urine, either for parent drugs and me tabolites. This method offers a sensitive assay for aminopyrine, dipyr one (widely consumed in some countries) and its metabolites. After ora l administration and collection of 24-h urine, this method allows the in vivo study of aminopyrine metabolism, which reflects liver function .